1. Field of the Invention
The present invention relates to investment cast molding tools for the manufacture of golf club heads. More specifically, the present invention relates to an investment cast molding apparatus for the construction of metal wood-type golf club heads.
2. Description of the Related Art
One of the oldest methods of forming golf club heads is through investment casting. This process is currently used to produce the majority of wood-type golf club heads. In this process, a resin mold, which includes two plates composed of aluminum hinged at one end and having a hollow center, is used. A master copy of the golf club head to be produced is suspended in the hollow center and a liquid resin is poured around the master copy to create the outer shape of the golf club head upon solidification of the resin.
In hollow metal wood-type golf club heads, the interior shape of the golf club head is produced by an aluminum core, which typically consists of five pieces. Wax is injected into the mold to fill the space between the inner and outer shapes of the golf club head. The mold is opened and the aluminum core with the wax pattern around it is removed. The aluminum core is separated from the wax pattern by first removing a center piece of the core. The remaining pieces of the core may then be shifted around and removed through the opening that was created by removal of the center core piece. When all of the pieces of the core have been removed, the wax pattern of the golf club head will have a large hole in the either crown or sole, through which the aluminum core was removed. This hole will be covered by a plate, which is typically welded about its perimeter to the golf club head. The weld is then sanded smooth to blend with the rest of the golf club head.
There are several areas with this apparatus and manufacturing process that could be improved. First, the removal of the core from the wax pattern and mold can be time-consuming and laborious. Typically, a tool is inserted into openings formed in the base of the core and used to pry the individual core pieces from the wax pattern and mold. The tool may slip and can damage the core, wax pattern and/or the mold. Second, extraction of the first core piece from the mold can create a suction force on the wax pattern, drawing the wax pattern away from the mold and damaging it. Third, the individual core pieces, which are designed to slide in a longitudinal direction with respect to each other so as to enable their removal from the wax pattern, lack a means for restricting movement in the longitudinal direction during insertion of the core into the cavity of the mold. Thus, as the core is being placed in the mold cavity, individual core pieces can slide relative to the others and damage either themselves or the mold.
Thus, there is a need for an improved aluminum core that stays together during insertion of the core in a mold and is easy to remove from a wax mold.